The hydrogen sulfide content of some naturally occurring gases, synthesis gases, process gases, and fuel gases produced by gasification procedures, e.g., gases produced by the gasification of coal, petroleum, shale, tar sands, etc., is often at environmentally unacceptable levels. In order to meet increasingly stringent total sulfur content requirements, effective procedures for removal of this contaminant from these "sour" gases are necessary.
One problem associated with the removal of H.sub.2 S from such streams is that the gases mentioned also commonly contain significant amounts of CO.sub.2 and COS. If the ratio of these gases to H.sub.2 S is high, difficulty is experienced in removing the H.sub.2 S selectively by absorption since the CO.sub.2 and COS will also tend to be absorbed. Obviously, any CO.sub.2 and COS removed with the H.sub.2 S must be contended with in further treatment steps. Although the CO.sub.2 can be vented, if separated from the H.sub.2 S, the COS cannot because of its poisonous character. On the other hand, the desorption characteristics at COS are similar to those of CO.sub.2, so that separation techniques are complicated. Finally, the diluting effect of large amounts of CO.sub.2 renders the practice of the "Claus Process" (in which H.sub.2 S is reduced to elemental sulfur) impractical or impossible. Aside from other considerations, capital costs necessary for recycle of large volumes of CO.sub.2, etc., would be prohibitive. Accordingly, there exists a genuine need for an economical method for removal of H.sub.2 S, and CO.sub.2 and COS (so-called acid gases) from desired gaseous streams which avoids these problems and disadvantages.